Feldman retired 18 straight on his way to his first career complete game, a three-hitter, and the Cubs took advantage of their former top pick's wildness in a 6-2 win over the San Diego Padres on Wednesday night.

''It's something I've been wanting to do for a while,'' Feldman said of the complete game. ''Always seemed like my pitch count got up or (I) got taken out a little before that could happen.''

After the eighth, Feldman (2-3) asked Cubs manager Dale Sveum if he could get a chance at his first complete game. Sveum obliged, and even though Feldman gave up a home run to Chase Headley, he finished the game and ended with a career-high 12 strikeouts while allowing just two runs, three hits and two walks.

Cashner (1-2) lasted four innings and gave up five runs, four earned, on six hits, four walks, a wild pitch and a hit batter. He was dealt to San Diego in January 2012 for Rizzo, who was 1 for 4 with a stolen base for the Cubs.

Feldman, who signed a one-year contract in November, has given up three runs in his last 15 2-3 innings for Chicago, which got its 16th quality start of the season.

After Headley singled with two outs in the first, Feldman retired the next 18 batters and didn't allow another Padres baserunner until Carlos Quentin reached on an error by third baseman Luis Valbuena.

Feldman's performance was especially welcome for the Cubs. On Tuesday starting pitcher Edwin Jackson booed off the mound after 4 2-3 innings, forcing them to tax their bullpen.

Feldman made sure that didn't happen Wednesday.

''It was as pure and crisp as you can imagine out of a guy that doesn't throw 98 mph,'' Sveum said. ''That was pretty impressive after what (San Diego) did last night.''

Feldman's performance, he also doubled in a run in the second, reminded the Cubs' Julio Borbon of what Feldman looked like when they were Texas Rangers teammates in 2009 and Feldman won 17 games.

Chicago Cubs starter Scott Feldman throws against the San Diego Padres during the first inning of a …

''It was good to see him back to being his old self,'' Borbon said. ''Happy for him.''

Cashner, who was victorious in his previous start April 26 against San Francisco, had trouble from the beginning and gave up runs in Chicago's first four innings.

''I was bad. I didn't command my fastball very well,'' the right-hander said.

''When I was missing it was just off the plate instead of going after guys. I really never got a feel for my secondary stuff in the strike zone.''

The Cubs took a 1-0 lead in the first on Starlin Castro's RBI single that drove in Borbon. Cashner eventually loaded the bases on a walk to Nate Schierholtz, but got out of the jam when he tagged Rizzo out at home after a pitch got past catcher John Baker.

Chicago Cubs' Scott Feldman hits an RBI double against the San Diego Padres during the second inning …

Chicago doubled its lead in the second when Darwin Barney scored on Feldman's double to right. It was Feldman's first hit in nine at-bats with the Cubs and his second career RBI.

The Cubs added two more runs in the third when Rizzo and Castro scored on Dioner Navarro's two-run double off the wall in right-center.

That was more than enough for Feldman, who drew high praise from Headley and compared his outing to Chris Carpenter and Roy Halladay.

''He was as good as anyone I've seen all year,'' he said. ''Both sides of the plate. Cutting it, sinking it. Changing speeds. Getting ahead in the strike zone. He was really good.''

NOTES: Cubs LF Alfonso Soriano was given the night off. He played in the Cubs' first 26 games, hitting .263 with one home run and two RBIs. ... Padres pitcher Tyson Ross worked 1 2-3 innings of relief Tuesday night in a rehab assignment with Triple-A Tuscon, allowing three hits, three runs and two walks while striking out two and throwing 43 pitches. Ross has been on the disabled list since April 20, retroactive to April 18, with a subluxation in his left, non-throwing shoulder. ... Cubs pitcher Matt Garza threw 2 2-3 innings Wednesday in a rehab assignment with Double-A Tennessee, allowing one hit and two walks on 42 pitches. Garza hasn't pitched for the Cubs yet this season after suffering a strained left lateral muscle during spring training. ... Thursday's pitching matchup is San Diego's Eric Stults (2-2, 5.67) against Chicago's Travis Wood (2-1, 2.25).